This invention relates to so-called tree savers and particularly to a packer cup assembly for use with tree savers.
Many oil and gas wells or the like have a so- called Christmas Tree assembly which includes various valves and special coupling means, for example, and which extends vertically from the well head. The Christmas Tree is coupled at its lower end to the well casing and (at least usually) to a string of tubing within the casing.
Many Christmas Trees are unable to withstand the high pressures used in present day well stimulation treatments. Other Christmas Trees, though able to withstand the pressures involved in the well stimulation treatment, might be physically harmed by the material being pumped into the well during its treatment.
Tree savers, conventionally coupled to the upper end of the Christmas Tree, have an internal movable mandrel which then is forced down through the Christmas Tree to seal at its lower end against the upper end of the tubing which is coupled to the lower end of the Tree.
In some tree savers the internal diameter of the movable mandrel must be substantially reduced in order for the lower end of the mandrel to accommodate a sealing assembly which seals against the upper end of the tubing string.
In another tree saver, the packer device at the lower end of the mandrel has a configuration such that it cannot seal against or enter any device in the Christmas Tree which is of smaller diameter than the internal diameter of the tubing.